骨质量对种植牵张初期稳定性影响的三维有限元分析

背景:种植体型牙槽嵴牵张器的初期稳定性取决于骨-牵张器界面适当的应力分布,了解植入初期的生物力学改变有助于提高种植体型牙槽嵴牵张器的临床成功率.目的:通过有限元法了解骨质结构对牵张初期应力分布和牵张器、骨段变形情况的影响.方法:利用CAD软件绘制由输送段和基段组成的牵张器模型(长11 mm,直径3.7～4.1 mm),同一软件绘制4个下颌骨节段模型模拟4类不同骨质的下颌骨.装配后导入ANSYS软件形成由10 079～11 456单元和17 299～20 101节点构成的有限元模型,利用该系列有限元模型分析松质骨、密质骨的应力改变和输送骨段、牵张器的变形情况.结果与结论:最大应力均出现在输送骨段,随骨质量下降而增大;骨最大变形出现在输送段边缘,随着骨质量下降而增大;牵张器的下沉也随着骨质量的下降而增大.结果表明随着骨质量的下降,最大应力与变形均明显增大.骨弹性模量的下降将增大牵张成骨失败的风险.

Influence of bone quality on initial stability of implantable distraction A three-dimensional finite element analysis

BACKGROUND: The initial stability of implantable distractor depends on the stress distribution of bone-distractor interface. The understanding of the biomechanical change in initial stage can improve the clinical success ratio of implantable distractor used in alveolar crest.OBJECTIVE: To evaluate the influence of bone quality on stress distribution and deformation in initial distraction stage.METHODS: Four three-dimensional models with 10 079-11 456 cells and 17 299-20 101 nodes were prepared by finite element methods (11 mm in length and 3.7-4.1 mm diameter). Implantable distractor was embedded in a segment of mandible. The elastic modulus of cancellous bone and the thickness of cortical bone, stress and deformation of bones and distractor were calculated.RESULTS AND CONCLUSION: The highest stress in the bone was concentrated in transportable section and the maximum deformation of transportable section was observed at the edge of the cortical bone, both of which were increased with bone quality decreased. The subsidence of distractor was observed with bone quality decreased. Bone quality influenced the initial stability and the result of the implantal distraction. The decrease of bone elastic modulus would increase the failure risk of distraction osteogenisis.